Wood separator and method of preparing same



Patented Aug. 9, 1927.

UNITED STATES PATENT OFFICE.

WILLIAM: II. enmnrrcn, or PHI ADELPHIA, PENNsYnvANIA, ASSIGNOR r urim: DELPHIA STORAGE BATTERY comPANY, or PHILADELPHIA, PENNSYLVANIA,

CORPORATION 01 PENNSYLVANIA.

\ 'woon SEPABATOR AND METHOD or PREPARING sAIIE.

' No Drawing.

One object of this invention is to providea novel succession of steps for the prepara tion'of a dry, porous, wood separator 'for .use in electrlc. batteries, and the invention I especially contemplates a method of drying separators which have been subjected to a wet, porosity-giving treatment, without thewithout ribs, suitably cut with an allowance for shrinkage across the grain, although, in

ordinary sizes, they may be cut to the desired finished length along the grain either before or after the treatment and drying.

The separators, individually or in con- 5 venient lengths, are first subjected to a wet treatment to remove resinous or other matter and increase their porosity; as for instance, they may be boiled in water or subjected to a treatment in a solution of caustic soda-or other suitable solvent.

After treatment, the wet separators are placed in a suitable dr er, supported between gratings of expand ed metal, wire netting or metal rods, or between ordinary bat-- tery plate grids. If made of iron, the supporting structures should be lead-coated or tinned to prevent rust, or they may bemade of Monel or similar non-rusting metal. The grating may he of any suitable. construction 4 which will allow currents of air 'from the fans of the dryer to enter between and act uniformlyon theseparat'ors and which will at the same time provide sufiicient mechanical support to overcome the tendency of the separators towarp 0nd g. v

The dryer is prefera ly equipped with humidity and temperature. controlling means so that currents of air of predetermined v shrink pendin teries.

- Application fled March 5, 1823. Serial No. 623,066.

"ity of the incoming air is run up to approximately 90% followin a short initial period at comparatively low umidity for the rapid remova of surface water. As the drying proceeds, the humidity is gradually reduced until practically all the free water has been removed from the separators,- at which point, practically dry air may be used to remove the last traces of free water.

Under these conditions, the drying out of the separators proceeds slowly and the e takes place evenly so that the tendency o' the wood to warp or curl is greatly reduced. Ordinarily, from one to three days will be required to dry wet treated separators bythe above described" method; but the time may be longer or shorter deon the type and design of separator, t e means for support, and the treat-. in and drying conditions, as well as upon at er factors. I

Wood separators preparedby the above described inethodcome out of the dryer flat and-will remain flat in stock until used. They are relatively porous as compared with similar separators of dry raw wood and at the same time possess good insulating roperties and ample mechanical strength or use between the plates of storage bat- 2. The method which comprlses the subjection of wet wood separators to the action V of warm air of progressively decreasing humidity.

3. The method of dryin wet wood separators which comprises su jec ting them to subjecting them to progressively drier air currents.

' thereafter 4. The method of drying wet wood sepathem to the action of air curren gressl'vel y decreasmg llu'mldlty.

ts of pro- 5. The method of drying wet Wood separators which comprises supporting said separators between gratings and subjecting them to the action of a current of Warm air of initially high and progressively decreasing humidity.

WILLIAM H. GRIMDITCH. 

